A Kurdish separatist group claimed responsibility for a large fire at Istanbul's Ataturk airport that injured three people, delayed international flights and destroyed the main cargo-handling building. The group's claim could not be independently verified.

Thick smoke from yesterday's blaze forced one runway closure, and about 2,000 workers had to flee the flames.

The Kurdistan Freedom Falcons Organisation, a hardline group linked to the main Kurdistan Workers' Party guerrilla group, said it started the fire to protest against Turkey's treatment of the Kurdish minority.

Government officials had earlier ruled out terrorism or sabotage and given various possible causes, including a spark from a welder's torch or an electrical short-circuit.

But a police official, speaking on condition of anonymity, said an investigation to determine the cause was still under way.

The fire destroyed much of the cargo in the building, including textiles and gold shipments worth millions of pounds.

Firefighting planes filled their hulls with six tons of water at a time from the nearby Sea of Marmara and made more than 70 trips to drop it on the burning building. Dozens of fire trucks helped, taking more than four hours to get the blaze under control.